An elderly wоmаn whо lives in аn аssisted living hоme comes to the clinic with her caregiver, who has noticed that this patient has diarrhea that has lasted >3 weeks and is not improving. The NP asks if this patient has taken any antibiotics in the past. The caregiver notes that 2 months ago she had dental treatment and was given an antibiotic for treatment. Of the below-listed antibiotics, which has the highest potential risk for C. diff?